1. Field of the Invention
The present invention relates to a scintillator panel, a radiation detecting apparatus and a radiation image pickup system adapted for use in a medical diagnostic equipment or a non-destructive inspection equipment, and particularly to a scintillator panel, a radiation detecting apparatus and a radiation image pickup system adapted for use in an X-ray image pickup. In the present specification, the radiation includes also electromagnetic waves such as α-ray, β-ray or γ-ray in addition to X-ray.
2. Description of the Related Art
For obtaining an X-ray photograph, there has been generally employed an X-ray film system including a fluorescent screen having an X-ray phosphor layer and an X-ray film coated on both sides. On the other hand, a digital radiation detection apparatus, including a phosphor layer as a wavelength converting member for converting an X-ray and a two-dimensional photodetector constituted by arranging photoelectric converting elements two-dimensionally, is an object of active research and development, and various patent applications are being made. This is based on a fact that the digital radiation detection apparatus has satisfactory image characteristics and digital data provided by such apparatus can be fetched into a computer system on a network and can provide an advantage of data sharing. Among such digital radiation detection apparatuses, an apparatus of a high sensitivity and a high sharpness is disclosed in U.S. Pat. No. 6,262,422, which describes a radiation detection apparatus formed by a photodetector (also called “sensor panel”) constituted of a photoelectric converting element unit in which plural switching elements such as photosensors and TFTs (thin film transistors) are arranged two-dimensionally and by forming thereon a phosphor layer for converting a radiation into a light detectable with the photosensor.
FIG. 11 is a cross-sectional view showing a prior radiation detection apparatus. Also FIG. 12 is a cross-sectional view of a radiation detection apparatus in which the aforementioned phosphor layer is formed in a two-dimensional sensor panel constituted of a photoelectric converting element unit in which plural electrical elements such as photosensors and TFTs are arranged. In FIG. 12, there are shown a glass substrate 101; a photosensor 102 utilizing amorphous silicon and constituting a photoelectric converting unit with a TFT; a wiring 103; a connection lead 104; a sensor protective layer (first protective layer) 105 formed for example with silicon nitride; a phosphor undercoat layer (second protective layer) formed by a resinous film 111; a phosphor layer 112 formed by an alkali halide having a columnar crystal structure; a phosphor protective layer 113 and a protective layer 115 for the reflective layer formed by an organic resin; a reflective layer 114; a protective resin 116 formed on the sensor panel on an external periphery of the phosphor prior to the formation of the phosphor protective layer 113, and a sealant 117 for sealing end portions of the phosphor protective layer 113 and the reflective layer protective layer 115 to prevent a moisture intrusion from the exterior thereby improving the durability. A connection lead 104 for a connection with an external electrical circuit is connected for example to a flexible wiring board, for example with an anisotropically conductive adhesion film. These components constitute a radiation detection apparatus.
In the aforementioned prior configuration, however, in case forming the phosphor layer 12 on the sensor panel, the connection lead 104 has to be masked in order to prevent a deposition of the phosphor, constituting the phosphor layer 112, onto the connection lead 104.
In this operation, it is possible to prevent the deposition of the phosphor by so positioning a holder, used for setting the sensor panel in an apparatus for evaporating the phosphor layer, as to cover the electrical connection lead 104. However, when the holder is detached after the formation of the phosphor layer, an electrostatic charge accumulated in the sensor panel may be discharged to the holder or the like, thereby causing, through the connection lead 104, a characteristic change of the photosensor 102 or the TFT or a breakage of a wiring, formed on the sensor panel. Also a masking may be achieved by covering the connection lead with a polyimide tape or the like before the setting in the phosphor forming apparatus, but there may result, when the masking tape is peeled off after the formation of the phosphor layer, a peeling charging of the sensor panel, thereby resulting in a discharge at a contact by the panel handling and causing similar failures. Also in the aforementioned masking by the masking tape, there may result a deposition of the phosphor on the connection lead 104 because of an incomplete masking or a residue of the tape on the collection lead 104, thus requiring a rinsing step of the connection lead 104 with a solvent or the like, thus increasing the manufacturing operations.
Also in the aforementioned prior technology, the phosphor protective layer 113 and the protective layer 115 for reflective layer are formed by a CVD (gaseous growth) method requiring a vacuum evaporation apparatus, but such process necessitates an expensive apparatus and a very long forming time, leading to a high cost.